Speech analyzers that analyze speech waveforms to extract feature parameters and speech synthesizers that synthesize speech based on the feature parameters obtained by speech analyzers have been widely used in speech processing techniques such as a text-to-speech synthesis technique, a speech coding technique and a speech recognition technique.
However, conventionally, there is a problem that there is a difficulty in use for a statistical model, or that a deviation occurs between a reconstructed phase and a phase of an analysis source waveform. In addition, conventionally, there is a problem that it is difficult to generate a waveform rapidly when generating the waveform using a group delay feature amount. An object of the present invention is to provide a speech processing device, a speech processing method, and a computer program product which make it possible to enhance reproducibility of a speech waveform.